1. Field of the Invention
The present disclosure relates generally to overrunning coupling devices such as one-way clutches and, more specifically, to electromechanically-actuated one-way clutches.
2. Related Art
This section provides background information related to the present disclosure which is not necessarily prior art.
Automatic transmissions provide a plurality of forward and reverse speed or gear ratios by selectively actuating one or more brakes or clutches. One type of brake or clutch widely used in modern automatic transmissions is a one-way clutch (OWC) which overrun when one of its races (in radial clutch arrangement) or one of its drive plates (in axial clutch arrangements) rotates in a first (i.e., freewheel) direction relative to the other race or drive plate, and it engages or locks in a second (i.e., lockup) direction. Such conventional overrunning coupling devices provide no independent control over their operation, that is to say whether they lockup or freewheel in both directions. Thus, basic one-way clutches provide a “locked” mode in one rotary direction and a “freewheel” mode in the opposite rotary direction based an the direction that a torque is being applied to the input member.
There are however, requirements in automatic transmissions where “controllable” overrunning coupling devices, commonly referred to as selectable one-way clutches (SOWC), are selectively controlled to provide additional functions. Specifically, a selectable one-way clutch may further be capable of producing a freewheel mode in both directions until a command causes the clutch to shift into its lockup mode. Thus, a selectable one-way clutch may be capable of providing a drive connection between an input member and an output member in one or both rotational directions and may also be operable to freewheel in one or both rotational directions.
In some instances, the SOWC in automatic transmissions often utilizes a high pressure hydraulic control system to selectively actuate the clutch and shift between the available operating modes. Examples of conventional selectable one-way clutches that are hydraulically controlled are disclosed in U.S. Pat. Nos. 8,079,453 and 8,491,439. In contrast, it is also known to provide an electromechanical actuator for the SOWC, examples of which are disclosed in U.S. Pat. Nos. 8,276,725 and 8,418,825. While such selectable one-way clutch configurations appear to meet all functional requirements, a need exists to continue development of new and improved selectable one-way clutches, especially the type that do not require high pressure hydraulics for actuation.